Generally, an air conditioning system is installed in a vehicle. Further, the air conditioning system includes a heating system for heating an indoor space of the vehicle, a cooling system for cooling the indoor space of the vehicle, and heating, ventilation and air conditioning (HVAC) controlling temperature/strength/direction of air introduced into the indoor space of the vehicle.
In the vehicle driven by fossil energy, engine cooling water is directly used as a heat source for heating the indoor space of the vehicle. That is, the cooling water that takes heat from an engine passes through the heater core in the HVAC and then is introduced into the engine again. During the process, the cooling water transfers heat to air passing through the heater core. Further, the air passing through the heater core is introduced into the indoor space of the vehicle to heat the indoor space of the vehicle.
FIG. 1 is a conceptual diagram of the existing vehicular heating device 10. As illustrated in FIG. 1, the existing vehicular heating device 10 is configured to allow cooling water to circulate a heater core 1 equipped in the HVAC, an engine 2, a water pump 3, a thermostat 5, and a radiator 6 to circulate cooling water. The cooling water heated by passing through the engine 2 is supplied to the heater core 1 and the indoor space of the vehicle is heated by exchanging heat generated in the heater core 1.
If a vehicle equipped with the existing vehicular heating device is driven, in particular, during a winter season, a driver experiences difficulties due to the cold. That is, since it takes much time until the cooling water supplied to the heater core 1 is sufficiently heated by the engine 2, there is a problem that the low temperature state inside the vehicle cannot but be continued for a predetermined period of time.
In particular, a diesel engine recently under development has excellent efficiency, such that a temperature rise of cooling water is delayed. That is, the excellent engine efficiency means that the engine can be operated with a minimum driving force, such that it takes a relatively long time to heat the cooling water circulating the engine. Accordingly, it takes a long time to heat the vehicle with the cooling water that absorbs the heat generated from the engine. In particular, the initial indoor heating performed immediately after the cold start during the winter season cannot but be more vulnerable.
Furthermore, as a heat source capable of increasing automatic transmission oil heating performance and engine oil heating performance is required to cope with recent fuel efficiency regulations, the heat source is insufficient during a low temperature start during a winter season and therefore the heating performance may be lowered. Further, a cooling water circulating pump for circulating the cooling water is interlocked with an rpm of an engine, and the rpm of the engine for each vehicle speed may be reduced due to a multistage of a transmission and therefore the circulation efficiency of the cooling water circulating pump may be lowered and a flow rate of the cooling water is insufficient and therefore the heating performance may be vulnerable.
In order to solve the above problem, there is a case where an auxiliary heater using electricity during the initial low temperature start is mounted on a heating part of the heater core 1. However, a discharge air volume of the heater core 1 may be reduced, and therefore there is a problem in that the efficiency of the initial indoor heating is still low during the winter season.